Abstract: A highly magnified view of a fruit fly's eye shows the light-sensitive cellular structures known as rhabdomeres. These specialized structures in the retina transform light into electrical impulses that the brain recognizes as "sight." Analogous structures serve the same function in humans. The fly's surprising genetic similarity to humans allows Nansi Colley, PhD, a UW Eye Research Institute scientist, to pinpoint mutations leading to macular degeneration, retinitis pigmentosa, and other vision-threatening diseases.